644668353 has 36 divisors (see below), whose sum is σ = 1112522580. Its totient is φ = 358416576.

The previous prime is 644668337. The next prime is 644668457. The reversal of 644668353 is 353866446.

644668353 is a `hidden beast` number, since 64 + 466 + 83 + 53 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 370832049 + 273836304 = 19257^2 + 16548^2 .

It is not a de Polignac number, because 644668353 - 2⁴ = 644668337 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644668299 and 644668308.

It is not an unprimeable number, because it can be changed into a prime (644668253) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3438 + ... + 36071.

It is an arithmetic number, because the mean of its divisors is an integer number (30903405).

Almost surely, 2^644668353 is an apocalyptic number.

644668353 is a gapful number since it is divisible by the number (63) formed by its first and last digit.

It is an amenable number.

644668353 is a deficient number, since it is larger than the sum of its proper divisors (467854227).

644668353 is a wasteful number, since it uses less digits than its factorization.

644668353 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39566 (or 39556 counting only the distinct ones).

The product of its digits is 1244160, while the sum is 45.

The square root of 644668353 is about 25390.3200649381. The cubic root of 644668353 is about 863.8641480397.

The spelling of 644668353 in words is "six hundred forty-four million, six hundred sixty-eight thousand, three hundred fifty-three".